Barron's 2nd Edition PT1 Q70

Barron's Book

70) This question asks us to find the theoretical efficiency of a heat engine operating between 100°C and 500°C. This means we are working with the Carnot Cycle.

The Carnot engine is a theoretical engine that operates at peak efficiency. This engine goes through the Carnot cycle, composed of 2 isothermal and 2 adiabatic processes as I’ve drawn in the Pressure-Volume diagram below.

Where P is pressure, and V is volume

The theoretical efficiency is described as the efficiency of the Carnot cycle.

Where e is efficiency, T[H] is the highest temperature in the operating range, and T[C] is the lowest temperature in the operating range

The question gives us the operating range so we need to convert our givens to degrees Kelvin and plug them into this expression.

Where e is efficiency

Answer: C